Wind energy conversion system

ABSTRACT

A wind energy conversion system includes upper and lower wind turbines having counter-rotating blade assemblies supported for rotation about a vertical rotation axis, with each blade assembly carrying a rotor for rotation past a stator to produce an electrical output. The wind turbines are supported by a tower at an elevated position above the ground. Each wind turbine produces torque, and the wind energy conversion system provides for balancing the torques to avoid a net torque on the tower. Adjustment mechanisms are provided for adjusting blade pitch and for adjusting the size of an air gap between a stator and a rotor that comes into alignment with the stator as the rotor rotates therepast. The wind energy conversion system provides a hood for supplying intake air to a wind turbine and an exhaust plenum for exhausting air from the wind turbine, with the hood and the exhaust plenum being directionally positionable.

CROSS-REFERENCE TO RELATED PATENT APPLICATIONS

This application is a divisional of prior U.S. patent application Ser.No. 10/883,214 filed Jul. 1, 2004 now U.S. Pat. No. 6,952,058, which isa continuation-in-part of prior U.S. patent application Ser. No.10/783,413 filed Feb. 20, 2004 and now abandoned, which claims priorityfrom prior provisional patent application Ser. No. 60/448,355 filed Feb.20, 2003, the entire disclosures of which are incorporated herein byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to wind energy conversionsystems in which kinetic energy of wind is converted into electric powerand, more particularly, to wind energy conversion systems having bladeassemblies carrying rotor elements for movement past stator elements toproduce electric current.

2. Brief Discussion of the Related Art

Current wind power technology has primarily been developed by adaptingor modifying non-wind technologies to wind power applications. Thisapproach has resulted in wind power systems of excessive weight andcost, which has limited the cost-effectiveness and acceptance of windpower systems as a viable option for electric power production. As anexample, a 500 KWe Vesta V39 wind power system typically weighs over 33tons and costs more than $1,000,000 installed. The capital cost of sucha system is around $2000 per KWe (about four times the capital cost of acoal plant), and the system weight translates to about 132 pounds perKWe. Consequently, the use of wind as a renewable energy source has notbeen taken full advantage of, and the wind power industry has notrealized its full potential.

Current wind power technology typically utilizes “wind turbines”, whichare in fact propellers normally of large diameter, i.e. 135 feet ormore, and including two, three, four or five blades rotatable about ahorizontal or nearly horizontal axis to effect rotation of a driveshaft. The propellers ordinarily rotate at extremely slow speeds due totheir substantial mass and the centrifugal force at the blade roots. Thedrive shafts must be very large and very heavy, as represented by thefollowing calculation of the size and weight needed for a solid steeldrive shaft to transmit torque in a 500 KWe wind turbine system at 1rpm.

$\begin{matrix}{{{K{We}} = \frac{0.746 \times {torque} \times {rpm}}{5,252}};} \\{{torque} = {\frac{5,252 \times K\;{We}}{0.746 \times {rpm}}.}}\end{matrix}$Where rpm equals 1 and KWe equals 500,

${torque} = {\frac{5,252 \times 500}{0.746 \times 1} = {\frac{2,626,000}{0.746} = {3,520,107\mspace{14mu}{{ft}.\text{-}}{{lbs}.}}}}$Assuming a yield strength of 10,000 psi for the solid steel drive shaft,

$d = {\left( {\left( {16 \times {torque}} \right) \div \left( {\pi \times 10,000\mspace{14mu}{psi}} \right)} \right)^{\frac{1}{3}} = {12.148\mspace{14mu}{{inches}.}}}$Assuming a safety margin of 4 for fatigue, the diameter of the driveshaft needed is 19.284 inches, and this massive drive shaft must berotated by the blades at low rpm. In addition, a drive shaft of thisdiameter is equivalent to 995 pounds per linear foot of the drive shaft.

Rotation of the drive shaft at low rotational speeds in prior windturbine systems must be increased or stepped up in speed to about 900 to3,600 rpm to drive a conventional generator. Increasing the drive shaftspeed to drive a generator requires a large, costly and heavy gearstep-up transmission assembly. The generator, weighing several tons,also contributes significant weight to the wind turbine system. Anaerodynamic housing, such as the Nacelle, is commonly used in prior windturbine systems to house equipment and typically weighs about 36,000pounds. The excessive weight of conventional wind turbine systemsnecessitates a massive and costly tubular steel tower to support thepropellers in an elevated position above the ground.

Conventional wind turbine systems commonly utilize positioning systemsincluding computers and hydraulics to position the propellers to faceinto the oncoming wind and to “feather” the propellers, i.e. turn thepropellers orthogonal to the wind in high wind conditions. One drawbackto these positioning systems is that they shut down under the highestpotential power output conditions.

Representative wind power systems are disclosed in U.S. Pat. No. 25,269to Livingston, U.S. Pat. Nos. 1,233,232 and 1,352,960 to Heyroth, U.S.Pat. No. 1,944,239 to Honnef, U.S. Pat. No. 2,563,279 to Rushing, U.S.Pat. No. 3,883,750 to Uzzell, Jr., U.S. Pat. No. 4,182,594 to Harper etal, U.S. Pat. No. 4,398,096 to Faurholtz, U.S. Pat. No. 4,720,640 toAnderson et al, U.S. Pat. No. 5,299,913 to Heidelberg, U.S. Pat. No.5,315,159 to Gribnau, U.S. Pat. No. 5,457,346 to Blumberg et al, U.S.Pat. No. 6,064,123 to Gislason, U.S. Pat. Nos. 6,278,197 B1 and6,492,743 B1 to Appa, U.S. Pat. No. 6,504,260 B1 to Debleser, and U.S.Pat. No. 6,655,907 B2 to Brock et al, in U.S. Patent ApplicationPublication No. US 2003/0137149 A1 to Northrup et al, and in GermanPatent DE 32 44 719 A1.

Only the Livingston patent discloses a blade assembly rotatable about avertical axis of rotation. The blade assembly of the Livingston patentrotates a drive shaft and does not carry a rotor element for rotationpast a stator element to produce electric current directly. Bladeassemblies that carry rotor elements for rotation past stator elementsto produce electric current are disclosed in the patents to Heyroth('232 and '960), Honnef, Harper et al, Anderson et al, Gribnau,Gislason, and Brock et al, in the U.S. Patent Application Publication toNorthrup et al and in the German patent, but the blade assemblies rotateabout horizontal axes of rotation. The blade assembly of the Honnefpatent comprises two counter-rotating wheels each having a rim carryingdynamo elements. The dynamo elements of one wheel rotate in oppositionto the dynamo elements of the other wheel to produce electricity. TheHonnef patent does not disclose two blade assemblies each capable ofproducing an electrical output independently. A wind power system havingtwo counter-rotating blade assemblies in which each blade assemblycarries rotor elements for rotation past stator elements is disclosed byHarper et al. Wind power systems having hoods for supplying air to theblade assemblies and having air intake openings facing lateral to therotation axes of the blade assemblies are represented by the Livingstonpatent and the Brock et al patent.

In light of the foregoing, there is a need for a wind energy conversionsystem having two blade assemblies supported for rotation in oppositedirections about a vertical rotation axis, with each blade assemblycarrying a rotor for rotation past a stator to produce an electricaloutput directly and independently. There is also a need for a windenergy conversion system having two wind turbines with blade assembliessupported for rotation in opposite directions wherein the torquesproduced by the wind turbines are capable of being balanced to avoid anet torque on the tower. A further need exists for a wind energyconversion system having a blade assembly supported for rotation about arotation axis, a hood disposed over the blade assembly having an airintake opening facing lateral to the rotation axis, and an exhaustplenum disposed beneath the blade assembly having an outlet opening,with the hood being rotatable about the rotation axis to maintain theair intake opening facing upwind and the exhaust plenum being rotatableabout the rotation axis to maintain the outlet opening facing downwind.Another need exists for a wind energy conversion system having a bladeassembly carrying a rotor for rotation past a stator to produce electriccurrent, wherein the size of the air gap between the rotor and thestator is adjustable to control output current voltage in response tochanges in rotational speed of the blade assembly.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the present invention to overcome theaforementioned disadvantages of prior wind power systems.

Another object of the present invention is to provide a wind energyconversion system utilizing upper and lower wind turbines having bladeassemblies rotated in opposite directions about a vertical rotationaxis.

A further object of the present invention is to utilize a guyed tower tosupport counter-rotating blade assemblies in an elevated position abovethe ground.

An additional object of the present invention is to adjust blade pitchfor counter-rotating blade assemblies of a wind energy conversion systemto control the rotational speed of the blade assemblies.

It is also an object of the present invention to adjust blade pitch forcounter-rotating blade assemblies of a wind energy conversion system toestablish nominal conversion of wind velocity into torque.

The present invention has as another object to provide a wind energyconversion system of reduced weight, mass and cost.

Moreover, it is an object of the present invention to adjust the size ofthe air gap between a stator and a rotor carried by a blade assembly forrotation past the stator to control output voltage in a wind energyconversion system.

Additionally, it is an object of the present invention to adjust thesize of the air gap between a stator and a rotor carried by a bladeassembly for rotation past the stator to control the rotational speed ofthe blade assembly in a wind energy conversion system.

The present invention has as an additional object to adjust thedirectional position for an outlet opening of an exhaust plenum tomaintain the outlet opening facing downwind in response to changes inthe directional position for an air intake opening of a hood facingupwind in a wind energy conversion system.

Yet a further object of the present invention is to configure the statorelement of a wind turbine to present an air gap of varying size inrelation to a rotor to produce a varying voltage output.

Still another object of the present invention is to rotate a rotor pastthe stator elements of three single phase generators and to time theoutput of the generators to obtain a three phase power output in a windenergy conversion system.

It is an additional object of the present invention to supply a watermist to the intake air in a wind energy conversion system.

Moreover, it is an object of the present invention to selectivelyarticulate a stator to selectively increase and/or decrease the size ofan air gap between the stator and a rotor carried by a blade assemblyfor rotation past the stator in a wind energy conversion system.

Still a further object of the present invention is to automaticallyadjust the size of an air gap between a stator and a rotor carried by ablade assembly for rotation past the stator in response to changes inrotational speed of the blade assembly such that output voltage changesare restricted.

The present invention has as another object to balance the torquesproduced by counter-rotating wind turbines of a wind energy conversionsystem to avoid net torque being exerted on a tower supporting the windturbines in an elevated position above the ground.

It is also an object of the present invention to relieve air pressurefrom an air intake hood to regulate maximum power and/or shear forces ina wind energy conversion system.

The aforesaid objects are achieved individually and in combination, andit is not intended that the present invention be construed as requiringtwo or more of the objects to be combined.

Some of the advantages of the present invention are that the wind energyconversion system may include one or more than one wind turbine, eachhaving a blade assembly; the blade assemblies do not drive a drive shaftas in prior wind turbine systems; the weight of the wind energyconversion system is greatly reduced permitting lighter and lessexpensive guyed towers, stabilized by guy cables, to be used to supportthe one or more wind turbines in an elevated position above the ground;optimum performance versus cost and weight may be accomplished byvarying the size of a center void and spinner for the blade assemblies;the air intake opening is maintained facing into the oncoming windwithout the need for power consuming equipment and/or computers todirect yaw; intake air is deflected by the spinner toward the effectiveblade area of the one or more wind turbines; blade structure iseliminated from the short radius, low torque position where virtually nopower is produced, thusly resulting in greater efficiency and decreasedweight; exhaust air is discharged from the one or more wind turbineswith greater efficiency, less back pressure on the one or more windturbines and enhanced laminar air flow; the wind energy conversionsystem allows the commutators and brushes associated with conventionalgenerators and which require maintenance and downtime to be eliminated;wind turbines of larger generating capacities can be supported at higherelevations to the advantage of greater wind speeds; greater power outputis obtained using less air space than prior wind turbine systems; thewind energy conversion system can be used to generate DC or AC power; agreater number of wind energy conversion systems can be deployed peracre of land than conventional wind turbine systems; each stator maycomprise a continuous stator element or a plurality of individual statorelements; each rotor may comprise a variable number of rotor elements;the blades of the blade assemblies have an airfoil configuration and areoptimally sized in relation to spaces between the blades; a rudderassembly operates in conjunction with the intake hood to producepositive yaw on the hood; the exhaust plenum is configured to create avacuum at the outlet opening; the outer rims of the blade assemblies aresupported and positioned between cooperating rollers; electric powerproduced by the one or more wind turbines may be stored in batteries,which may be charged under control of a charging controller; the torquecreated by each wind turbine can be monitored in various ways; mildcompression in the hood increases the velocity of the air through theturbines, thereby enhancing output at lower input wind speeds; theexhaust plenum may be designed to assist directional yaw; operation ofthe water misters may be controlled so that only water misters locatedadjacent the air intake opening are turned on; and output from the watermisters may be controlled in accordance with the electrical output ofthe one or more wind turbines.

These and other objects, advantages and benefits are realized with thepresent invention as generally characterized in a wind energy conversionsystem comprising an upper wind turbine, a lower wind turbine disposedbelow the upper wind turbine, a tower supporting the wind turbines in anelevated position above the ground, and a balancing mechanism forbalancing the torques produced by each wind turbine to avoid a nettorque on the tower. The upper wind turbine includes a stator, a bladeassembly mounted for rotation about a vertical rotation axis in responseto air flow through the upper wind turbine, and a rotor carried by theblade assembly for rotation past the stator to produce an electricaloutput. The lower wind turbine comprises a stator, a blade assemblymounted for rotation about the vertical rotation axis in response to airflow through the lower wind turbine, and a rotor carried by the bladeassembly of the lower wind turbine for rotation past the stator of thelower wind turbine to produce an electrical output. The blade assemblyof the upper wind turbine rotates in a first direction about thevertical rotation axis while the blade assembly for the lower windturbine rotates in a second direction, opposite the first direction,about the vertical rotation axis.

Each rotor preferably comprises a plurality of permanent magnets thatcome into alignment with the corresponding stator as the magnets rotatein a rotational path. The stator for each wind turbine preferablycomprises a plurality of stator coils spaced from one another along therotational path for the corresponding magnets. The stator for each windturbine may comprise three single phase generators each having a statorcoil along the rotational path, with the output of the generators beingtimed to obtain a three phase electrical output. Each stator coil maycomprise a pair of curved stator coil segments, with the stator coilsegments curving away from the plane of the rotational path to producean electrical output of changing voltage.

Each blade assembly may comprise an inner rim, an outer rim concentricwith the inner rim and a plurality of blades extending between the outerand inner rims radial to the vertical rotation axis. The balancingmechanism may comprise a pitch adjustment mechanism for each windturbine for adjusting the pitch angle of the blades. The balancingmechanism may include an air gap adjustment mechanism for each windturbine for adjusting the size of an air gap between the stator of thewind turbine and the rotor of the wind turbine that comes into alignmentwith the stator as the rotor rotates therepast. The wind energyconversion system may comprise a hood disposed over the upper windturbine for supplying intake air to the wind turbines and an exhaustplenum disposed below the lower wind turbine for exhausting air awayfrom the wind turbines. One or more strain gages or other monitors maybe provided for monitoring turbine torque.

The present invention is further generally characterized in a windenergy conversion system comprising a wind turbine having a stator, ablade assembly mounted for rotation about a vertical rotation axis inresponse to air passing through the wind turbine, a rotor carried by theblade assembly for rotation past the stator to produce an electricaloutput, a tower supporting the wind turbine in an elevated positionabove the ground, and an air gap adjustment mechanism for adjusting thesize of an air gap between the stator and the rotor which comes intoalignment with the stator as it rotates therepast. The rotor is carriedby the blade assembly in a rotational path disposed in a plane, and therotor comes into alignment with the stator as it rotates in therotational path. The air gap is defined between the stator and the rotorwhen the rotor is in alignment therewith.

The air gap adjustment mechanism includes a track along which the statoris movable toward and away from the plane of the rotational path torespectively decrease or increase the size of the air gap. The air gapadjustment mechanism may include a housing mounting the stator with thehousing being movable along the track. The track can mount the housingfor movement of the stator along a direction perpendicular to the planeof the rotational path. The stator may be mounted by the housing at apredetermined location along the rotational path, and the stator mayremain at this location while being moved in the direction perpendicularto the plane of the rotational path. The track can mount the housing formovement of the stator along a direction at an acute angle to the planeof the rotational path, with the stator moving along the rotational pathas it is moved along the track toward or away from the plane of therotational path. The stator may be moved automatically along thedirection at an acute angle to the plane of the rotational path toincrease the size of the air gap in response to increased drag force onthe stator due to increased rotational speed of the blade assembly. Thestator may be moved automatically along the direction at an acute angleto the plane of the rotational path to decrease the size of the air gapin response to decreased drag force on the stator due to decreasedrotational speed of the blade assembly. The air gap adjustment mechanismmay comprise a resilient restraining member applying a force on thestator in opposition to increased drag force on the stator. The air gapadjustment mechanism may further comprise a strain gage for monitoringtorque produced by the wind turbine.

The present invention is also generally characterized in a wind energyconversion system comprising a wind turbine having a stator, a bladeassembly mounted for rotation about a vertical rotation axis in responseto air passing through the wind turbine, a rotor carried by the bladeassembly for rotation past the stator to produce electrical power, atower supporting the wind turbine in an elevated position above theground, a hood disposed over the wind turbine and an exhaust plenumdisposed beneath the wind turbine, with the hood and the exhaust plenumeach being directionally positionable. The hood defines an air intakepassage for supplying intake air to the wind turbine and has an intakeopening facing lateral to the vertical rotation axis for taking in airand a discharge opening for discharging the air toward the wind turbine.The hood is rotatable about the vertical axis to maintain the intakeopening facing upwind. The exhaust plenum defines an exhaust passage forexhausting air from the wind turbine and has an outlet opening facingaway from the vertical rotation axis for exhausting the air from theexhaust plenum. The exhaust plenum is rotatable about the verticalrotation axis to maintain the output opening facing downwind. Theexhaust plenum may be rotated via a drive mechanism in response torotation of the hood. The hood may include relief ports for relievingexcess intake air from the hood. The wind energy conversion system mayinclude a water misting system for releasing water into the intake air.The wind energy conversion system may comprise upper and lower windturbines with the hood disposed over the upper wind turbine and theexhaust plenum disposed beneath the lower wind turbine.

Other objects and advantages of the present invention will becomeapparent from the following description of the preferred embodimentstaken in conjunction with the accompanying drawings, wherein like partsin each of the several figures are identified by the same referencecharacters. Various components or parts of the wind energy conversionsystem have been partly or entirely eliminated from or partly orentirely broken away in some of the drawings for the sake of clarity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a broken side view of a wind energy conversion systemaccording to the present invention.

FIG. 1B is a side view of the wind energy conversion system.

FIG. 2 is a broken side view depicting upper and lower wind turbines ofthe wind energy conversion system.

FIG. 3 is a top view of the upper wind turbine.

FIG. 4 is a broken side view of a wind turbine depicting an air gapadjustment mechanism.

FIG. 5 is a broken top view of a wind turbine depicting an alternativeair gap adjustment mechanism.

FIG. 6 is a broken view depicting the alternative air gap adjustmentmechanism looking radially outwardly from the vertical axis of rotationfor the wind turbines.

FIG. 7 is a broken view, partly in radial section, of the alternativeair gap adjustment mechanism.

FIG. 8 is a top view of a wind turbine illustrating a blade pitchadjustment mechanism with the associated blade in a minimum pitch angleposition.

FIG. 9 is a broken side view of the blade pitch adjustment mechanismwith the associated blade in a maximum pitch angle position.

FIG. 10 is a broken view illustrating attachment of a link of the bladepitch adjustment mechanism to a control rod of the associated blade.

FIG. 11 is a top view of the wind energy conversion system illustratingan intake hood, a rudder assembly for the intake hood and a mistingsystem for the wind energy conversion system.

FIG. 12 is a broken fragmentary view depicting a drive mechanism for anexhaust plenum of the wind energy conversion system.

FIG. 13 is a broken view of a wind turbine depicting an alternativestator element designed to produce a power output of varying voltage.

FIG. 14 represents wiring of the alternative stator element to producealternating current.

FIG. 15 is a top view of a wind turbine depicting a stator comprisingthree single phase generators.

FIG. 16 illustrates timing of the single phase generators to produce athree phase power output.

FIG. 17 is a broken fragmentary view depicting a mister control valvefor the misting system.

FIG. 18 illustrates a representative control logic schematic for thewind energy conversion system.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

A wind energy conversion system or wind power system 10 according to thepresent invention is illustrated in FIGS. 1A and 1B and comprises upperand lower wind turbines 12 a and 12 b forming an electrical generator, atower 14 supporting the wind turbines 12 a and 12 b at an elevatedposition above the ground for rotation about a vertical rotation axis15, an air intake hood or snorkel 16 disposed over the upper windturbine 12 a for directing intake air to the wind turbines, a rudderassembly 18 for positioning the hood 16, and an exhaust plenum 20disposed beneath the lower wind turbine 12 b for exhausting air from thewind turbines. Although the wind energy conversion system 10 is shown ascomprising upper and lower wind turbines 12 a and 12 b, it should beappreciated that the wind energy conversion system may comprise a singlewind turbine, such as wind turbine 12 a or 12 b, forming the electricalgenerator as disclosed in prior provisional patent application Ser. No.60/448,355 filed Feb. 20, 2003 and incorporated herein by reference.Each wind turbine 12 a and 12 b produces an electrical power outputdirectly and independently via rotors carried by blade assemblies of thewind turbines rotating past stators of the wind turbines, respectively.Power output from the wind turbines is supplied to an electrical device22 which may comprise an electrical load and/or an electrical storagedevice such as a battery bank comprising one or more batteries.

Wind turbines 12 a and 12 b are essentially identical and are bestillustrated in FIGS. 2 and 3, it being noted that various components ofthe wind energy conversion system described and/or illustrated hereinhave been omitted from FIGS. 1A and 1B for the sake of clarity. FIG. 3depicts the upper wind turbine 12 a but is also applicable to the lowerwind turbine 12 b. Each wind turbine 12 a and 12 b comprises a bladeassembly including an inner circumferential rim 24 having the rotationaxis 15 as its central axis, an outer circumferential rim 25 concentricwith the inner rim 24, and a plurality of blades 26 extending betweenthe inner and outer rims radial to the rotation axis 15. The bladeassemblies are spaced from one another along the vertical rotation axis15, with each blade assembly rotating in a horizontal planeperpendicular or essentially perpendicular to the rotation axis 15. Thehorizontal planes of rotation for the blade assemblies of the upper andlower wind turbines 12 a and 12 b are therefore in spaced parallelrelation. The blade assemblies for the upper and lower wind turbines 12a and 12 b are essentially identical to one another, but the blades forthe upper wind turbine 12 a have a pitch angle oriented in opposition tothe pitch angle of the blades of the lower wind turbine 12 b such thatthe blade assemblies for the upper and lower wind turbines are rotatedin opposite directions about the rotation axis 15 by air flowing throughthe blade assemblies. As shown by arrows in FIG. 2, the blade assemblyfor the upper wind turbine 12 a, i.e. the upper blade assembly, rotatescounterclockwise about the rotation axis 15 while the blade assembly forthe lower wind turbine 12 b, i.e. the lower blade assembly, rotatesclockwise about the rotation axis 15. The use of counter-rotating windturbines is advantageous for reducing torque on tower 14. As shown inFIG. 2, which shows fewer blades than FIG. 3, each blade 26 has across-sectional configuration of an air foil with a thicker leading edgefacing the direction of rotation and a thinner trailing edge. As seen inFIGS. 2 and 3, each blade 26 has a width that tapers from an outer endto an inner end of the blade, and the annular area between the outer andinner rims 24 and 25 of each blade assembly presents spaces 27alternating with the blades 26. Each blade 26 may be economicallyconstructed as an outer skin or layer of aluminum, fiberglass or moldedplastic filled with expandable foam for rigidity.

Each blade 26 is mounted on a control rod 28 disposed radial to therotation axis 15. The control rods 28 pass through the blades 26,respectively, and each control rod 28 defines a pitch axis 29, radial tothe rotation axis 15, about which the corresponding blade is rotatableto adjust the blade pitch angle as explained further below. The blades26 for each blade assembly are disposed within the annular area definedbetween the outer rim 25 and the inner rim 24 of the blade assembly,with the pitch axes 29 at equally spaced radial locations about therotation axis 15 as best seen in FIG. 3. The number of blades 26 foreach blade assembly may vary and, as depicted in FIG. 3, each bladeassembly may have ten blades 26 and ten spaces 27 alternating with theblades 26. Preferably, the spaces 27 for each blade assembly account forabout 50 percent of the area between the inner rim 24 and the outer rim25. The inner rim 24 for each blade assembly circumscribes a void asvirtually no power is produced at the short radius, low torque position.A control drum 30 is disposed within and fills both voids and is securedto the tower. When only one turbine is employed, the blade assembly mayconsist of a full compliment of blades without spaces 27.

A spinner 31 extends above the blade assembly for the upper wind turbine12 a. The spinner 31 and the control drum 30 are coaxial, with thespinner 31 being configured to present minimum aerodynamic resistanceand preferably having the configuration of a rocket nosecone. Thecontrol drum 30 is disposed in the voids circumscribed by the inner rims24 of the blade assemblies coaxial with the rotation axis 15. Thespinner 31 is attached to one of the blade assemblies and rotatestherewith. Preferably, the control drum 30 is a hollow structure forenhanced rotation and reduced drag and weight.

As shown in FIG. 2 spinner 31 may be attached to the blade assembly forthe upper wind turbine 12 a for rotation therewith, and the spinner canbe attached to the blade assembly in various ways including the use offasteners 34. The fasteners 34 may be bolts as shown in FIG. 2 or anyother suitable fasteners to join spinner 31 to the upper surface ofinner rim 24. The bolts may extend through a shoulder of spinner 31 andinto the inner rim 24. As shown in FIG. 2, a support 32 isconcentrically disposed within the control drum 30 with there being amating thread between the control drum 30 and the support 32 asexplained further below. The control drum 30 may be rotatable relativeto the support 32, which may be rigidly connected to a stem 41 fixed tothe tower 14. The spinner 31 deflects intake air in the hood 16 towardthe blades 26 for maximum turbine efficiency. The sizes of the voids andspinner are calculated as the trade-off between potential capacity ofthe voided area and the added cost and weight for the spinner.

As shown in FIGS. 1A and 1B, the tower 14 comprises a frame 36supporting the upper and lower wind turbines 12 a and 12 b, a base 37supporting the frame 36 in an elevated position above the ground, andguy cables 38 providing additional support and/or stability to the frame36 and/or the base 37. The base 37 is vertical and coaxial with therotation axis 15. The base 37 may be designed in various ways withexternal or internal reinforcement. The frame 36 may be designed invarious ways of various configurations presenting openings for thedischarge of exhaust air from exhaust plenum 20 as explained furtherbelow. The frame 36 preferably comprises three or more frame members 36′and an essentially cylindrical containment structure 39 circumscribing acontainment area for the upper and lower wind turbines 12 a and 12 b.Only part of the containment structure 39 is shown in FIGS. 1A, 1B and 2for the sake of clarity to permit visualization of the wind turbines.The containment structure 39 may have any suitable internalconfiguration or parts needed to mount other components of the windenergy conversion system. The frame members 36′ may include a pluralityof spaced apart frame members or struts 36′ supporting the containmentstructure 39, with spacing between the frame members 36′ allowing thedischarge of exhaust air. The number and location of frame members 36′may vary depending upon the size of the containment structure and/or thenumber and location of components to be attached to the frame 36. Theframe 36 is preferably coaxial with the base 37 and rotation axis 15.The frame 36 has one or more support flanges 40 at its upper endextending in a radially outward direction. The one or more flanges 40is/are disposed around or circumscribe an entry opening at the top ofcontainment structure 39 providing communication with the containmentarea. The flange 40 may be a single flange continuous around the entryopening or a plurality of spaced apart flanges. The spinner 30 mayinclude the stem 41 extending from the support 32 to the base 37, withthe stem 41 passing through the exhaust plenum 20. The guy cables 38 maybe secured between the frame 36 and/or the base 37 and the ground.

The blade assemblies of the upper and lower wind turbines 12 a and 12 bare supported or mounted within the containment area of containmentstructure 39 for rotation in the horizontal planes about the rotationaxis 15. The outer rim 25 of each blade assembly is rotatably supportedor mounted by or on a plurality of mounting devices 42 secured to frame36. Preferably, at least three mounting devices 42 are secured to thecontainment structure 39 about the outer rim 25 of each wind turbine 12a and 12 b at spaced radial locations about the rotation axis 15. Tosupport the weight of and ensure minimum flux in a blade assembly havinga relatively large diameter outer rim 25, mounting devices 42 wouldadvantageously be located at 2 to 4 foot intervals about the outercircumference of the outer rim 25 or as determined empirically. As bestseen in FIGS. 2 and 4, each mounting device 42 comprises a bracket 43and a pair of upper and lower rollers 44 a and 44 b mounted on thebracket 43. The brackets 43 are secured to the one or more frame members39 so as to be disposed within the containment area, and the brackets 43may be secured to the one or more frame members 39 in various waysincluding the use of fasteners 45. The fasteners 45 may comprise boltsextending through the one or more frame members 39 and into the bracketsor may comprise any other suitable fasteners. Each bracket 43 has a pairof upper and lower arms respectively mounting the upper and lowerrollers 44 a and 44 b at opposing 45 degree angles to the horizontalplane of rotation of the corresponding blade assembly. The upper andlower rollers 44 a and 44 b may be rotatably mounted on respective axleshaving ends secured, respectively, to the upper and lower arms of thebracket 43.

The upper and lower rollers 44 a and 44 b for each mounting device 42cooperate to support the corresponding outer rim 25. As shown in FIG. 2,the outer rim 25 of each wind turbine 12 a and 12 b is tapered along itsouter circumference to present upper and lower outer circumferentialsurfaces angled toward one another from the upper and lower surfaces,respectively, of the outer rim at 45 degree angles to meet at an outercircumferential edge. The outer circumferential edge of each outer rim25 is positioned between the upper and lower rollers 44 a and 44 b ofeach associated mounting device 42 for respective sliding engagement ofthe upper and lower outer circumferential surfaces with the upper andlower rollers 44 a and 44 b of the mounting device. Each outer rim 25 isthusly supported and guided for rotation in its horizontal plane ofrotation as permitted due to rotation of the upper and lower rollers 44a and 44 b about their respective axles. The outer circumferential edgeof each outer rim 25 is captured between the upper and lower rollers 44a and 44 b of the corresponding mounting devices 42, whereby each bladeassembly is supported and positioned vertically and horizontally whilebeing capable of rotation in its horizontal plane in response to airpassing through the blade assembly.

The blade assemblies are vertically spaced from one another with theirhorizontal planes of rotation in parallel relation. A plurality ofstraightener vanes or stabilizers 82 may extend vertically between theblade assemblies radial to the rotation axis 15. The vanes 82 may beattached to the containment structure 39 as shown in FIG. 2. A brake 35may be provided for the blade assembly of each turbine 12 a and 12 b asshown in FIG. 3 for the upper wind turbine 12 a, it being noted thatcontainment structure 39 and mounting devices 42 are not shown in FIG. 3for the sake of simplicity. The brake 35 may including a brake element46 selectively engageable with the outer rim 25 with a frictionalcontact to slow or stop the rotation of the blade assembly.

Each wind turbine 12 a and 12 b includes a stator 48 supported on thecontainment structure 39 and a rotor 49 carried by the blade assemblyfor rotation past the stator 48 to produce an electric current output.As best shown in FIG. 3, the stator 48 for each wind turbine 12 a and 12b comprises one or more stator elements 50 such as one or more statorcoils. The rotor 49 for each wind turbine 12 a and 12 b comprises one ormore rotor elements 51, preferably one or more permanent magnets. Therotor elements 51 are illustrated in FIGS. 2 and 3 as permanent magnetscarried in recesses along the upper surfaces of the outer rims 25, butthe rotor elements 51 could be carried in recesses along the lowersurfaces of the outer rims. A plurality of rotor elements 51 is providedfor each outer rim 25 at spaced radial locations about the rotation axis15 and, as shown in FIG. 3, the rotor elements 51 are provided atequally spaced radial locations about the rotation axis 15. The numberof rotor elements 51 for each wind turbine 12 a and 12 b may vary, withthe outer rim 25 of the upper wind turbine 12 a being shown by way ofexample in FIG. 3 with thirty six permanent magnets as the rotorelements 51. The rotor elements 51 for each wind turbine 12 a and 12 bare thusly arranged in a circle on the corresponding outer rim 25 androtate about the rotation axis 15 in a circular rotational path ofmovement disposed in a horizontal plane.

Each wind turbine 12 a and 12 b has its stator elements 50 in verticalalignment with the rotational path of movement of its rotor elements 51.The number of stator elements 50 for each wind turbine can vary and, asshown in FIG. 3, each wind turbine 12 a and 12 b can have three statorcoils as the stator elements 50 at spaced locations along the rotationalpath of movement of the corresponding rotor elements 51 and in closeproximity to the corresponding rotor elements 51. The stator elements 50may be disposed at equally spaced radial locations about the rotationaxis 15 as also shown in FIG. 3. A stator element 50 comprising a singlestator coil extending continuously along the rotational path of movementof the corresponding rotor elements 51 and in close proximity to thecorresponding rotor elements 51 could be provided for each wind turbine;however, the use of a plurality of shorter length stator coils spacedapart from one another and disposed at discrete locations along therotational path of movement of the rotor elements allows materials,weight and cost to be reduced. As the blade assemblies rotate in thehorizontal planes about the vertical rotation axis 15, the velocity ofthe rotor elements 51 pass the corresponding stator elements 50 inducesan electromotive (emf) force which causes electric current to begenerated in the stator elements 50, which are electrically coupled toelectrical device 22 forming an electric circuit. Direct current isproduced when the rotor elements 51 are rotated past the stator elements50 with the same pole (north or south) in the same direction.

As best illustrated in FIG. 4, the stator elements 50 for each windturbine 12 a and 12 b are mounted on or supported by the containmentstructure 39 with an air gap 52 between the stator elements 50 and thecorresponding rotor elements 51 that come into vertical alignment withthe stator elements as the rotor elements rotate therepast. In theillustrated embodiment, in which the rotor elements 51 are disposedalong the upper surfaces of the outer rims 25, the stator elements 50for the upper wind turbine 12 a are disposed directly above the uppersurface of the outer rim 25 of the upper wind turbine 12 a in verticalalignment with the rotational path of movement for the correspondingrotor elements 51, and the stator elements 50 for the lower wind turbine12 b are disposed directly above the upper surface of the outer rim 25of the lower wind turbine 12 b in vertical alignment with the rotationalpath of movement for the corresponding rotor elements 51. It should beappreciated that, where the rotor elements 51 are mounted along thelower surfaces of the outer rims 25, the stator elements 50 can bedisposed directly below the lower surfaces of the outer rims 25,respectively. The stator elements 50 can be mounted to the containmentstructure 39 in various ways to provide an air gap 52 of fixed orvariable size.

FIG. 4 illustrates an air gap adjustment mechanism 54 for mounting astator element 50 to the containment structure 39 in a manner permittingadjustment of the size of the air gap 52 between the stator element 50and the corresponding rotor elements 51 that come into verticalalignment with the stator element as the blade assembly rotates aboutthe vertical axis of rotation. The air gap adjustment mechanism 54includes a support 55 secured to the frame member 39, a drive screw 56carried by the support 55, an air gap control motor 57 for rotatablydriving the drive screw 56, a captive drive nut 58 carried by the drivescrew 56 for rotation therewith, and a housing 59 attached to the drivenut 58 and keyed to the support 55 such that the housing cannot rotate.The support 55 can be designed in various ways and, as shown in FIG. 4,the support 55 is designed as a hanger having a horizontal arm extendinginwardly from the containment structure 39 in a direction radial to thevertical rotation axis 15 and a vertical arm depending from an inner endof the horizontal arm. An outer end of the horizontal arm is secured tothe containment structure 39, and the horizontal arm can be secured tothe containment structure in various ways such as using one or morebolts or any other suitable fasteners 60. The drive screw 56 extendswithin the vertical arm with its central longitudinal axis parallel tothe vertical rotation axis 15. An end of the drive screw 56 extendsthrough the drive nut 58 into the housing 59, which is slidably disposedon a lower end of the vertical arm. The housing 59 has a bottom endcarrying the stator element 50 and is positioned by the support 55 suchthat the stator element 50 is in vertical alignment with the rotationalpath of movement for the corresponding rotor elements 51. The support 55and housing 59 position the stator element 50 in close proximity to therotor elements 51 that come into vertical alignment with the statorelement 50 but with an adjustable air gap 52 between the stator element50 and a rotor element 51 vertically aligned therewith. The housing 59is capable of vertical movement relative to and along the vertical armof the support 55, the housing 59 being movable upwardly and downwardlyin a vertical direction parallel to the vertical rotation axis 15, i.e.along the central longitudinal axis of the drive screw 56, as shown byan arrow in FIG. 4.

Since the housing 59 is prevented from rotating, rotation of the drivescrew 56 in a first direction, e.g. clockwise, by the air gap controlmotor 57 causes the housing to move vertically upwardly along thecentral longitudinal axis of the drive screw 56 and the stator element50 moves therewith to increase the size of the air gap 52 between thestator element 50 and the rotor element 51 vertically aligned therewith.Conversely, rotation of the drive screw 56 by the air gap control motor57 in a second direction, opposite the first direction, e.g.counterclockwise, causes the housing to move vertically downwardly alongthe central longitudinal axis of the drive screw 56, and the statorelement 50 moves therewith to decrease the size of the air gap 52between the stator element 50 and the rotor element 51 verticallyaligned therewith. The support 55 and particularly the vertical armthereof defines a track along which the housing 59 and stator element 50are movable toward and away from the plane of the rotational path ofmovement for the rotor elements 51 to selectively decrease and increasethe vertical size of gap 52. In the case of air gap adjustment mechanism54, the stator element 50 is moved along the track in a directionperpendicular to the plane of the rotational path of movement for therotor elements 51 while remaining at a fixed location along therotational path of movement. The air gap control motor 57 can beoperated manually or automatically via suitable controls to obtain aselected size for the air gap 52. An air gap adjustment mechanism 54 maybe provided for each stator element 50. The air gap adjustment mechanism54 may be used to establish the size of the air gap 52 and the size ofthe air gap may remain fixed while the voltage of direct currentproduced by each wind turbine is allowed to vary with changingrotational speeds for the blade assemblies. The output current ofvarying voltage may be supplied to a battery bank, i.e. electricaldevice 22, and may be supplied via computer controls to an appropriatenumber of battery cells for charging.

FIGS. 5–7 depict an alternative air gap adjustment mechanism 154 forvarying the size of the air gap 52 between a stator element 50 and therotor elements 51 that come into vertical alignment with the statorelement, it being noted that various components of the wind turbinedepicted in FIGS. 5–7 have been omitted for the sake of simplicity. Theair gap adjustment mechanism 154 provides automatic output voltagecontrol for the wind turbine and may serve as a balancing mechanism forbalancing the torques produced by the wind turbines 12 a and 12 b asexplained further below. The air gap adjustment mechanism 154 comprisesa support 155 secured to containment structure 39, a housing 159disposed on the support 155 for movement in an arcuate path, and aresilient restraining member 161 for the housing 159. The support 155defines a stationary track for the housing 159 along the arcuate path,with the track following the curvature of the rotational path ofmovement for the corresponding rotor elements 51. The track can bedesigned in various ways and may comprise one or more cam rods 162 eachhaving first and second ends secured to containment structure 39 and anarcuate configuration between the first and second ends corresponding tothe arcuate path of movement for the housing 159. As best seen in FIGS.6 and 7, the support 155 comprises a pair of vertically aligned andparallel cam rods 162. The cam rods 162 and, therefore, the trackdefined thereby are non-parallel to the horizontal plane of therotational path of movement for the corresponding rotor elements 51 andare angled upwardly from their first ends to their second ends relativeto this horizontal plane as best seen in FIG. 6.

The housing 159 is slidable along the track defined by cam rods 162 formovement therealong in the arcuate path. The housing 159 can be disposedon the track in various ways and, in the illustrated embodiment, the camrods 162 pass through respective bores in the housing 159. The bores mayeach be fitted with a bearing 163 receiving the corresponding cam rod162 therethrough. The stator element 50 is disposed on and carried bythe housing 159. When the housing 159 is slidably disposed on the camrods 162, the stator element 50 is positioned in vertical alignment withthe rotational path of movement of the rotor elements 51, with therebeing an air gap 52 between the stator element 50 and the rotor elements51 that come into vertical aligned therewith. The air gap 52 is variablein size in that the upward angle of the track defined by cam rods 162results in the vertical size of the air gap 52 increasing as the housing159 moves forwardly along the track, i.e. in the direction of the secondends of the cam rods, and decreasing as the housing 159 moves rearwardlyalong the track, i.e. in the direction of the first ends of the camrods. The forward direction of movement for the housing 159 correspondsto the rotational direction, i.e. clockwise or counterclockwise, for theouter rim 25 of the corresponding blade assembly.

The restraining member 161 applies a resilient force in the rearwarddirection against the housing 159 to resist movement of the housing inthe forward direction along the track defined by cam rods 162. Therestraining member 161 can be designed in various ways to apply therearward force and may include a spring as shown in FIGS. 5 and 6. Thespring may comprise a coil spring located to the rear of the housing 159and having opposing ends attached to the housing 159 and the containmentstructure 39, respectively. It should be appreciated that other types ofsprings may be used as the restraining member 161.

The rotor elements 51 are rotated in the forward direction by the outerrim 25 rotating in the forward direction. The outer rim 25 depicted inFIGS. 5–7 corresponds to the outer rim of the lower wind turbine 12 b,in which case the forward direction is clockwise as shown by arrows inFIG. 5. The arrows shown in FIG. 6 to indicate the clockwise forwarddirection are reversed from the arrows of FIG. 5 since FIG. 6 depictsthe inner circumference of the outer rim 25 looking radially outwardlyfrom the rotation axis 15. In the case of the outer rim 25 of the upperwind turbine 12 a, the forward direction would be counterclockwise. Asthe rotor elements 51 are rotated in the forward direction past thestator element 50 carried by housing 159, the counter electromotiveforce (emf) of the stator element 50 resists the forward motion of therotor elements 51. Drag is induced and is applied to the housing 159 asa force in the forward direction. Where the forward drag force on thehousing 159 does not exceed the rearward restraining force of therestraining member 161 on the housing 159, the housing 159 and thestator element 50 carried thereon are restrained from movement in theforward direction along the track defined by cam rods 162 such that thevertical size of the air gap 52 is maintained. As the rotational speedof the blade assembly increases, the emf drag increases. Where theforward drag force on the housing 159 increases to the extent that itovercomes the rearward restraining force on the housing 159 fromrestraining member 161, the housing 159 moves forwardly along the trackdefined by cam rods 162, and the stator element 50 moves correspondinglywith the housing as depicted in FIG. 6. Movement of the housing 159 andstator element 50 forwardly along the track from a first position to asecond position causes an increase in the vertical size of the air gap52 since the housing 159 and stator element 50 move upwardly relative toand away from the plane of the rotational path of movement of the rotorelements 51 due to the angle of the track defined by cam rods 162. Whenthe drag force on the housing 159 no longer exceeds the rearward forceof the restraining member 161, as when the rotational speed of the bladeassembly slows down, the resiliency of the restraining member 161automatically moves the housing 159 and stator element 50 rearwardlyalong the track defined by cam rods 162 from the second position towardthe first position such that the air gap 52 decreases in size as thestator element 50 moves downwardly relative to and toward the plane ofthe rotational path of movement of the rotor elements 51. Where therestraining member 161 is a coil spring, forward movement of the housing159 from the first position to the second position causes the spring tostretch or elongate, and rearward movement of the housing from thesecond position toward the first position causes the spring to contract.Movement of the housing 159 and stator element 50 along the trackdefined by cam rods 162 is non-perpendicular to the plane of therotational path of movement for the rotor elements 51 in that movementof the housing and stator element along the track occurs in a directionat an acute angle to the plane of the rotational path of movement. Also,the stator 50 does not remain at a fixed location along the rotationalpath of movement as it moves along the track. Rather, the stator element50 moves along the rotational path of movement while also movingupwardly/downwardly relative to the plane of the rotational path ofmovement, and the arcuate configuration of the track ensures that thestator element 50 remains vertically aligned with the rotational path ofmovement. Increasing and/or decreasing the vertical size of the air gap52 in response to changes in rotational speed of the blade assemblyrestricts voltage changes in the output current produced by the windturbine as a result of changing rotational speeds. An air gap adjustmentmechanism 154 can be provided for each stator element 50 of each windturbine 12 a and 12 b. Additional computer controls can be used to allowair gap control to regulate turbine rpm.

The wind energy conversion system 10 may include monitors 64 formonitoring and controlling torque created by the wind turbines 12 a and12 b, and the monitors 64 may comprise strain gages as shown in FIGS. 5and 6. Preferably one or more monitors 64 such as strain gages is/areprovided for each wind turbine 12 a and 12 b. The monitor 64 for eachwind turbine 12 a and 12 b may be deployed in various ways and atvarious locations to monitor torque. In the arrangement depicted inFIGS. 5 and 6, the monitor 64 is disposed on containment structure 39adjacent the connected end of the restraining member 161 and provides ameasurement of turbine torque as applied to the containment structure.Another way of monitoring turbine torque can be accomplished bymeasuring the wattage (voltage×current) of the electrical output of eachwind turbine 12 a and 12 b using suitable instruments. It is preferredthat torque be monitored for each wind turbine 12 a and 12 b using botha strain gage and wattage measurements. Monitoring turbine torque allowsthe torques produced by the upper and lower wind turbines 12 a and 12 bto be balanced to avoid a net torque being applied to the tower 14.Balancing the torques of the upper and lower wind turbines 12 a and 12 bis also achieved by adjusting the size of the air gaps 52 of the upperand lower wind turbines as explained above and/or adjusting the turbineblade pitch angle as explained further below.

A blade pitch adjustment mechanism 66 for selectively adjusting bladepitch angle is depicted in FIGS. 8–10 and may be used as a balancingmechanism to balance the torques produced by the upper and lower windturbines. As shown in FIGS. 8–10, the control rod 28 for each blade 26is preferably hollow and has inner and outer ends extending beyond theinner and outer ends, respectively, of the blade 26. The inner and outerends of the control rod 28 are supported to permit rotation of thecontrol rod 28 about its central longitudinal axis, i.e. the pitch axis29 shown in FIG. 3. The inner and outer ends of the control rod 28 maybe rotatably supported in inner and outer bearings 67 and 68,respectively, mounted on the inner and outer rims 24 and 25,respectively, of the blade assembly. As depicted in FIGS. 8 and 9, thebearings 67 and 68 may be mounted on the upper surfaces of the inner andouter rims 24 and 25, respectively. A portion of the inner end of thecontrol rod 28 protrudes beyond the inner bearing 67 in the direction ofthe vertical rotation axis 15. The blade 26 is secured to its controlrod 28 and rotates therewith when the control rod is rotated about itscentral longitudinal axis, the blade 26 rotating within the annular areabetween the inner and outer rims 24 and 25. The control rod 28 islocated to be passive in that the area of blade 26 disposed on each sideof its control rod is equal, and the air pressure cancels torque forceson the control rod.

The blade pitch adjustment mechanism 66 comprises a link 70 having afirst end connected to the inner end of the control rod 28 and a secondend connected to a cam follower 71, a swivel joint 72 connecting thesecond end of the link 70 to the cam follower 71, a cam 73 fastened tothe control drum 30 and having a groove 74 in its outer surface withinwhich the cam follower 71 is captured, and an actuator 75 for actuatingthe cam 73 to move the cam follower 71 within groove 74. The first endof link 70 is fixedly connected to the inner end of the control rod 28,and the first end of the link may be fixedly connected to the inner endof the control rod in various ways. As best shown in FIG. 10, the firstend of the link 70 may be bifurcated to define a pair of parallelfingers 76 and the inner end of the control rod 28 that protrudes beyondthe inner bearing 67 may be disposed between the fingers 76 with a closefit. A securing element 77 secures the inner end of control rod 28 inplace between the fingers 76. The link 70 has an arcuate longitudinalconfiguration with an inward curvature facing the vertical rotation axis15 and has an arcuate central longitudinal axis disposed in a plane. Thecam follower 71 comprises a roller that is rotatable about a centralaxis radial to rotation axis 15, thusly enabling the cam follower 71 toslide along the groove 74. The swivel joint 72 that connects the secondend of link 70 to the cam follower 71 allows the link to rotate or pivotrelative to the cam follower 71 about a pivot axis radial to thevertical rotation axis 15. The cam 73 comprises a cylindrical cam sleevedisposed concentrically over the control drum 30 and fastened thereto asshown in FIG. 9. The groove 74 is a circumferential groove along theexterior surface of the cam 73 and oriented perpendicular to therotation axis 15. The cam follower 71 is disposed in the groove 74 witha close fit while being slidable within the groove in a circumferentialdirection about the vertical rotation axis 15. The cam 73 fastens tocontrol drum 30 which has an internal thread 78 in cooperative threadedengagement with an external thread 79 along the support 32 of thespinner 30, and these threads may be Acme threads. Of course, it shouldbe appreciated that the control drum 30 may be provided with the camgroove 74 and may thusly form the cam 73. The threaded coupling orengagement between the control drum 30 and the support 32 results invertical movement of the control drum 30, and cam 73 therewith, relativeto and along the support 32 in response to rotation of the control drum30 and/or cam 73 relative to the support 32 and about the verticalrotation axis 15. Rotation of the control drum 30 and/or cam 73 relativeto the support 32 in a first direction, e.g. clockwise, about thevertical rotation axis 15 causes vertical movement of the cam 73 alongsupport 32 in a first vertical direction, e.g. upwardly. Rotation of thecontrol drum and/or cam 73 relative to the support 32 in a seconddirection, e.g. counterclockwise, opposite the first direction and aboutthe vertical rotation axis 15 causes vertical movement of the cam alongsupport 32 in a second vertical direction, e.g. downwardly, opposite thefirst vertical direction. The actuator 75 effects rotation of thecontrol drum 30 and/or cam 73 relative to the support 32 in the firstand second rotational directions and may comprise a cam control motor.The cam control motor may be used to impart rotation to the cam 73 byrotatably driving a drive ring 80 attached to the cam 73, and the drivering may be driven via a worm screw driven by the cam control motor. Aspring, such as a spiral spring, may be provided at the first end of thelink 70 or at any other suitable location to provide a spring force tomaintain the cam follower 71 in engagement with the groove 74.

FIG. 9 shows the cam 73 in a first vertical position along the support32 corresponding to a first rotational position for the link 70 in whichthe plane containing the central longitudinal axis of the link isvertical, is radial to the vertical rotation axis 15 and isperpendicular to the corresponding outer rim 25. In this position, theblade 26 mounted on the control rod 28 is at a maximum pitch angle andmay be considered as being in a fully open blade position or maximumpitch angle position. The cam follower 71 is engaged in groove 74, whichis in a first vertical position vertically spaced below the control rod28. In order to change the pitch of blade 26, the actuator 75 isactuated to effect rotation of the cam 73 about the vertical rotationaxis 15 in the direction needed to cause movement of the cam 73 upwardlyalong and relative to the support 32, as permitted by the threadedcoupling between the control drum 30 and the support 32. As the cam 73moves upwardly, the cam follower 71 slides within the groove 74, causingthe link 70 to rotate or pivot about its pivot axis as permitted byswivel joint 72. FIG. 8 illustrates the cam 73 moved upwardly to asecond vertical position along the support 32 corresponding to a secondrotational position for the link 70 in which the plane containing thecentral longitudinal axis of the link is horizontal, is perpendicular tothe vertical rotation axis 15 and is parallel to the horizontal plane ofrotation of the corresponding blade assembly. In this position, the link70 is rotated or pivoted 90 degrees from the position illustrated inFIG. 9, such that the control rod 28 and the blade 26 mounted thereonare correspondingly rotated 90 degrees about the pitch axis from theposition shown in FIG. 9. The blade 26 is at a minimum pitch angle andmay be considered as being in a fully closed blade position or a minimumpitch angle position. The blade 26 may be moved from the fully closedposition toward the fully open position by reversing the rotation of thecam 73 to effect downward movement of the cam along the support 32. Theamount of upward and downward vertical movement of the cam 73 can beselectively controlled to obtain various intermediate vertical positionsfor the cam 73 between the first and second vertical positions therefor.In this way, various intermediate rotational positions between the firstand second rotational positions can be obtained for the link 70 toachieve various intermediate positions for the blade 26 between thefully open and fully closed blade positions.

The cam 73 can be moved longitudinally along the support 32 in variousalternative ways including the use of hydraulic or pneumatic cylindersand linear screw actuators. The link 70 may pivot in both clockwise andcounterclockwise directions about its pivot axis such that the blade 26may rotate in both clockwise and counterclockwise directions about thepitch axis. A link 70 and cam follower 71 may be provided for each blade26 of each wind turbine 12 a and 12 b. A separate groove 74 may beprovided for each cam follower 71, or all of the cam followers 71 of awind turbine may be disposed in the same groove 74. A single actuator 75may be provided for both wind turbines 12 a and 12 b, or an actuator 75may be provided for each wind turbine 12 a and 12 b. The blade pitch forwind turbines 12 a and 12 b may be independently adjustable. Adjustingthe blade pitch allows the torque of each wind turbine 12 a and 12 b tobe controlled and balanced to limit a net torque on the tower 14. Wherethe straightener vanes 82 are disposed between the upper wind turbine 12a and the lower wind turbine 12 b, the straightener vanes are of a sizeand configuration to accommodate rotation of the blades 26 to the fullyopen position as shown in FIG. 2.

As illustrated in FIG. 1A, the air intake hood or snorkel 16 is fixedlyor rigidly mounted on a platform 84 that is rotatably supported on theone or more flanges 40 for rotation of the platform 84 about thevertical rotation axis 15. The platform 84 includes a planar upperplatform member 85 and a planar lower platform member 86 attached to theupper platform member in overlapping arrangement. The platform 84 has anopening or hole therethrough in vertical alignment over the entryopening at the top of frame 36 and is of sufficient size to provide anunobstructed path through the entry opening to the containment area andthe wind turbines 12 a and 12 b disposed therein. The platform openingextends through the upper platform member 85 and the lower platformmember 86. The upper platform member 85 may be attached to the lowerplatform member 86 in various ways including the use of fasteners suchas bolts extending through the platform members. Of course, the upperand lower platform members 85 and 86 could be formed integrally,unitarily or monolithically such that the platform 84 may be a one piecemember.

The lower platform member 86 has a circular peripheral configuration,and the lower platform member is tapered along its outer circumferencewith angled upper and lower circumferential surfaces as explained abovefor the outer circumference of the outer rims 25. A plurality ofmounting devices 42 are disposed on the one or more flanges 40 with theouter circumference of the lower platform member 86 between the upperand lower rollers of the mounting devices 42. The upper and lowerrollers of each mounting device 42 are in cooperative engagement withthe angled upper and lower circumferential surfaces of the lowerplatform member 86 as explained above for the outer rims 25. The lowerplatform member 86 is thusly mounted on the frame 36 for rotation in ahorizontal plane about the vertical rotation axis 15, with the upperplatform member 85 rotating with the lower platform member. The upperplatform member 85 has a peripheral configuration and size to mount thehood 16 and the rudder assembly 18 as explained further below.

The hood 16 is supported on the upper platform member 85 and is rigidlyor fixedly attached to the platform 84. The hood 16 may be attached tothe platform 84 using fasteners such as bolts. In this regard, thebottom of the hood 16 may be formed with an outwardly turned flange, andthis flange may be bolted to the platform 84. Accordingly, the hood 16rotates with the platform 84 about the vertical rotation axis 15. Thehood 16 comprises a hollow structure extending upwardly and laterallyfrom a discharge opening at the bottom of the hood disposed in alignmentwith the platform opening to an air intake opening 89 facing lateral tothe vertical rotation axis 15. The hood structure may be of uniform ornon-uniform cross-section between the discharge and air intake openings.Preferably, the discharge opening of the hood is circular and ofsufficient peripheral size to provide unobstructed communication throughthe platform opening to the containment area of frame 36 within whichwind turbines 12 a and 12 b are disposed. The intake opening 89 may berectangular in a vertical plane, which may be parallel to the verticalrotation axis 15, and the cross-section of the hood may transition fromrectangular to circular between the intake and discharge openings. Thesize of the intake opening is sufficiently large to provide an adequateintake of air for passage through the hood 16 and platform opening tothe wind turbines 12 a and 12 b. The intake opening 89 may be largerthan the circumference of the wind turbines, which allows the size ofthe wind turbines to be reduced. Mild air compression through the hood16 increases the velocity of intake air to the wind turbines 12 a and 12b and enhances power output from the wind turbines at lower wind speeds.A plurality of relief ports 90 are disposed in the outer wall of thehood 16 and may be selectively opened and closed, or opened under excessair pressure, via flaps 91, respectively. The flaps 91 may be pivotallymounted to the hood 16 and may be spring or gravity loaded so as to openthe relief ports 90 and relieve excess intake air from the hood 16 abovethe design input for the wind turbines. The relief ports 90 also limitshear force on the tower 14 in high wind conditions and allow the windenergy conversion system 10 to continue to output maximum power in highwinds.

The rudder assembly 18 maintains the intake opening 89 of the hood 16facing the direction of oncoming wind such that the intake opening ismaintained upwind, i.e. in or toward the direction from which the windblows as shown by arrows in FIG. 1A. As best seen in FIGS. 1A, 1B and11, the rudder assembly 18 is disposed on upper platform member 85opposite the intake opening 89 of hood 16 and comprises a pair ofrudders 92 extending upwardly from the upper platform member 85. Therudder assembly 18 is disposed on an opposite side of the rotation axis15 from the intake opening 89, and each rudder 92 has a forward edge, arearward edge and a top edge connecting the forward and rearward edges.The forward edges extend angularly upwardly in a direction away from thevertical rotation axis 15 at a non-perpendicular angle to the planarupper platform member 85. The rearward edges extend perpendicular to theupper platform member 85, and the top edges are parallel to the upperplatform member 85. The rearward edges terminate at a vertical planeperpendicular to the upper platform member 85 and this plane is parallelto a plane containing the intake opening 89. As depicted in FIG. 1A, therudders 92 have a torque arm distance X from the plane of rotation axis15 that is greater than the torque arm distance Y of the hood 16 fromthe plane of the rotation axis 15. Also, the rudders 92 have collectivesurface areas greater than the surface area of the hood 16. FIG. 1Aillustrates the rudder 92 having a collective surface area R1 on oneside of the vertical rotation axis 15, i.e. to the right side of thevertical rotation axis as depicted in FIG. 1A. The surface area of thehood 16 as seen in FIG. 1A may be considered as comprising surface areasections R2, L1 and L2. Surface area sections R2 and L2 are symmetricalto the vertical rotation axis 15 and are equal in size on oppositesides, i.e. right and left, of the vertical rotation axis 15. Surfacearea section L1 is disposed on the opposite side of the verticalrotation axis 15 from the rudder surface area R1, i.e. to the left ofthe vertical rotation axis 15 in FIG. 1A. The surface area section L1 issmaller in size than the rudder surface area R1. Surface area section L1provides negative yaw on the hood 16 while the rudder surface area R1provides positive yaw thereon since the surface area sections R2 and L2cancel and do not contribute to yaw. The positive yaw on the hood 16 isgreater than the negative yaw thereon, thereby providing a net positiveyaw causing rotation of the platform 84 about the vertical rotation axis15 in accordance with directional wind conditions such that the intakeopening 89 of the hood is kept facing into the oncoming wind.

The following is a representative yaw calculation for outer rims 25 thatare 20 feet in diameter, a torque arm distance X of 25 feet, a torquearm distance Y of 12 feet and a rudder surface area R1 25% larger thanthe hood surface area section L1:Yaw=R1×X−L1×Y;Yaw=1.25×25−1×12=+19.25Yaw is therefore positive and controlled by the rudder assembly 18 tomaintain the intake opening 89 of the hood 16 facing into the wind. Therudder assembly 18 maintains the intake opening 89 upwind without theneed for power consuming equipment and/or computers to direct yaw.

The exhaust plenum 20 has an annular supporting 94 at its topcircumscribing an opening disposed beneath the lower wind turbine 12 b.The support ring 94 is rotatably supported on containment structure 39by a plurality of mounting devices 42 mounted on the containmentstructure 39 at radial locations about the vertical rotation axis 15. Asdescribed above for the outer rims 25 and the lower platform member 86,the outer circumference of support ring 94 is formed by angled upper andlower circumferential surfaces in respective engagement with the upperand lower rollers of the mounting devices 42. Accordingly, the exhaustplenum 20 is mounted on the frame 36 for rotation about the verticalrotation axis 15. The exhaust plenum 20 is rotatably supported by theframe 36 beneath the lower wind turbine 12 b with the opening at the topof the exhaust plenum in vertical alignment with the containment area offrame 36 which accommodates the wind turbines 12 a and 12 b. The exhaustplenum 20 comprises a hollow exhaust structure that extends downwardlyand laterally from its top opening to an outlet opening 95. The exhauststructure has a cross-section that increases in size between its topopening and the outlet opening 95 to promote expansion and reduceturbulence and skin drag for exhaust air through the exhaust plenum 20.The exhaust structure is configured with a flared or bell mouth at theoutlet opening 95, causing external air to be deflected over the exhaustplenum and inducing a vacuum at the outlet opening 95 to assist airexhaust and reduce back pressure on the wind turbines 12 a and 12 b. Theexhaust plenum 20 has a through hole therein appropriately located andsized for passage therethrough of the stem 41 of the support 32. Theconfiguration for the exhaust plenum 20 depicted in FIG. 1A has aneutral impact on yaw for hood 16. However, it should be appreciatedthat the exhaust plenum 20 can be configured to extend further beyondthe vertical rotation axis 15, to the right in FIG. 1, to provideadditional structure that would provide positive yaw and assist incontrolling yaw on the hood 16.

The outlet opening 95 of the exhaust plenum 20 faces a directiongenerally opposite the direction that the intake opening 89 faces andthusly faces downwind, i.e. in or toward the direction in which the windblows as shown by arrows in FIG. 1A. A drive mechanism 96 is depicted inFIG. 12 for rotating the exhaust plenum 20 about the vertical rotationaxis 15 in accordance with rotation of the hood 16 to maintain theoutlet opening 95 facing downwind as the position of the intake opening89 changes to face upwind. The drive mechanism 96 comprises a drivecoupling 97 mounted to the platform 84, a drive coupling 98 mounted tothe support ring 94 of the exhaust plenum, a hydraulic pump and motorunit including a hydraulic pump 99 operated by the drive coupling 97 tocirculate fluid through a hydraulic motor 100 to drive the exhaustplenum via the drive coupling 98 in driving engagement with the motor100. The motor 100 may be controlled via a hydraulic brake control 101.The hydraulic pump 99 circulates fluid through the motor 100 in responseto rotation of the platform 84 about the vertical rotation axis 15, andthe motor 100 drives the support ring 94 to rotate the exhaust plenum 20about the vertical rotation axis 15. Various alternative drivearrangements may be used as the drive mechanism 96 including directshaft couplings, sprockets and chains, gears, tension cables, and/or cogbelts. Although a drive mechanism 96 is provided for the exhaust plenum20, it should be appreciated that the exhaust plenum can be designed torotate in unison with the hood 16 without a drive mechanism. Moreover,rotation of the exhaust plenum 20 can be effected independently of thehood 16 with a separate, independent drive mechanism or by designing theexhaust plenum to be self-positioning.

FIGS. 13 and 14 illustrate an arrangement by which AC power may begenerated by a wind turbine of the wind energy conversion system 10.FIG. 13 illustrates a stator element 150 comprising a pair of curvedstator coil segments 150 a and 150 b extending along the rotational pathof movement for rotor element 51. The curvature of the stator coilsegments 150 a and 150 b provides an air gap 152 of non-uniform sizebetween the stator element 150 and the plane of the rotational path ofmovement for the rotor element or elements 51 rotating past the statorelement 150. The non-uniform or varying size of air gap 152 causes anelectrical output of changing voltage to be produced. As represented inFIG. 14, the stator coil segments 150 a and 150 b may be wired to theelectrical device 22 output with opposing function and collectivelyproduce an electrical output having an AC sine wave.

FIG. 15 depicts an arrangement in which three-phase electrical power maybe produced as output by a wind turbine of the wind energy conversionsystem 10. FIG. 15 illustrates three stator elements 250, eachcomprising a single phase generator providing a single phase electricaloutput and having a stator coil disposed along the outer rim 25 of thewind turbine. The single phase generators are disposed at equally spacedradial locations about the vertical rotation axis 15 for mechanicalstrength and rigidity, but could be disposed at any one or morelocations. The single phase electrical outputs of the stator elements250 are timed to produce a three-phase electrical power output depictedin FIG. 16, which depicts the three-phase electrical power outputobtained by timing the single-phase outputs of the stator elements 250.The generators may be AC or DC. The generators may be driven by gears,belts or other means. The three single-phase generators have theadvantage of being lighter in weight and lower in cost than onethree-phase generator. Where AC generators are used, the additional costand complexity associated with AC generators should be considered.

An optional water misting system for the wind energy conversion system10 is depicted in FIG. 11. The water misting system comprises a waterdistribution manifold 103 extending circumferentially about the lowerplatform member 186, a water control valve 104 controlling the supply ofwater to the manifold 103 from a water source, and a plurality of watermisters 105 disposed along the manifold 103 at radially spaced locationsabout the vertical rotation axis 15. The water control valve 104 may beoperated in response to the electrical output of the wind energyconversion system 10 so that water to the manifold 103 is shut off whenthe wind is not blowing and/or so that the water supply to the manifold103 is increased/decreased as the electrical output increases/decreases.The water misters 105 are supplied with water from the manifold 103 fordischarge from the misters in a spray-like fashion. A mister controlvalve 106 of the water misting system is depicted in FIG. 17 and isoperated by a cam adjacent or along the intake opening 89 of hood 16 toopen only the water misters 105 that are situated in front of the intakeopening. A sufficient number of water misters 105 are provided at asufficient number of radial locations about the vertical rotation axis15 to ensure that at least one water mister 105 is disposed in front ofthe intake opening 89 for each directional position of the intakeopening about the vertical rotation axis 15. The water misting systemallows a water mist to be supplied to the intake air entering the intakeopening 89 to improve the efficiency of the wind energy conversionsystem 10. Evaporation of the water mist cools the incoming air andincreases its density, allowing more pounds of air to enter the hood 16.A water mist also assists in maintaining a laminar flow of intake airthrough the hood 16.

A representative control logic schematic for the wind energy conversionsystem 10 is depicted in FIG. 18. The control logic schematic depicts atorque monitor or strain gage 64 for each wind turbine 12 a and 12 b toprovide readings indicative of direct twist torque on the tower 14.Three stator elements 50 may be provided for each wind turbine 12 a and12 b with a voltmeter 107 for each stator element. The wind energyconversion system 10 may also include a master voltmeter 108 to providedata and assist controls. The stator elements 50 are stator coils shownconnected in series, which reduces rotational speed, the number of rotorelements or magnets, and the amount of coil windings needed to provide adesired output voltage. Wiring the stator coils in parallel wouldincrease the rotational speed, the number of rotor elements or magnetsand/or the amount of coil windings required to produce the same voltagebut would allow the use of smaller gauge wire for the coils by reducingthe current required through each coil. A tachometer 109 and a bladepitch indicator 111 are provided for each wind turbine 12 a and 12 b toprovide data and assist in controls. An indicator 113 is provided forthe hood 16 to provide data relating to operation and yaw of the hood16. An anemometer 117 is provided for measuring wind force and/or windvelocity. The electrical device 22 is seen as a battery storage bankhaving terminal remote operated circuit breakers 119 for chargingcontrol. An air gap controller 121 processes torque data, voltage data,and rpm data and adjusts the stator elements to achieve a balancebetween emf drag on the turbines. The air gap controller 121 cooperateswith other controls to maintain optimum performance of turbine rpm forwind energy conversion. An air gap control motor 57 is provided for eachstator element 50 to control the size of the air between the statorelements and the rotor element rotating therepast. An electrical controlsystem or charge controller 123 monitors each battery and may be used toalert operators when a battery requires maintenance or replacement as afunction of its charge rate, discharge rate and/or battery state. Thecharge controller 123 can be used to allow the output voltage of thewind turbines 12 a and 12 b to drop to a minimum value while stillcharging the battery bank 22. For example, in light winds providing lowvoltage, e.g. 24 volts, the charge controller 123 can still tricklecharge the battery bank by switching to a bank voltage just below theturbine output voltage. The control logic schematic shows batteries 2–6being charged via closed circuit breakers at terminals plus 1 and minus7 with 120–124 volts. The number of batteries being charged changes asthe output voltage from the turbines change. Full voltage, e.g. 288volts in the example shown in the control logic schematic, is maintainedby adjusting the air gap and/or the blade pitch angle via the air gapcontroller 121 and/or the blade pitch controller 147 for as long as thewind is above a minimum threshold, and the wind energy conversion system10 continues to function at a lower power output but still full voltageusing the variable charging system. Accordingly, the electrical controlsystem 123 allows controlled charging of the batteries as a function ofvarying output from the wind turbine(s) while maintaining full voltagevia an inverter system 169. The blade pitch controller 147 receivesinput indicative of torque on the tower, turbine rpm and turbine outputvoltage, and the blade pitch controller 147 outputs a control signal tothe blade pitch control motors 75 to regulate rpm for mechanical safety,voltages and tower stress due to turbine torque. A safety computer 153receives data inputs including turbine rpm, torque and voltages. Thesafety computer 153 may also receive data inputs from a manual control165 and/or any other safety features incorporated in the wind energyconversion system 10. The output of the safety computer 153 may operatebrakes, circuit breakers and any other function that it is desirable toshut down in the event of problematic performance. An inverter system169 including a solid state inverter may be provided for drawing powerfrom the DC battery bank and converting that power from DC to AC. Theinverter system 169 may also be used to regulate voltage output from thewind energy conversion system 10. Power from the batteries may be usedto drive a DC motor which drives an AC generator. Output power from thewind energy conversion system 10 may be used to power or operate varioustypes of DC and AC electric loads.

In operation, the upper and lower wind turbines 12 a and 12 b aresupported by tower 14 in an elevated position above the ground. The hood16 is self-positioning via the rudder assembly 18 to ensure that theintake opening 89 of the hood is directionally positioned to face intothe oncoming wind. Intake air enters the intake opening 89 and passesthrough the hood 16 and the platform 84 to the wind turbines 12 a and 12b. The spinner 31 deflects the intake air within hood 16 away from thecenter of the turbines to the effective blade area of the turbines. Airpassing downwardly through the containment area of the containmentstructure 39 rotates the blade assemblies of the upper and lower windturbines 12 a and 12 b in opposition to one another about the verticalrotation axis 15, since the pitch angle for the blades 26 of the upperwind turbine is in opposition to the pitch angle for the blades 26 ofthe lower wind turbine 12 b. In the illustrated embodiment, the bladeassembly of the upper wind turbine 12 a rotates counterclockwise aboutthe vertical rotation axis 15 when looking from above while the bladeassembly for the lower wind turbine 12 b rotates clockwise about thevertical rotation axis 15 when looking from above. As the bladeassemblies rotate, the rotor elements 51 carried by their outer rims 25are rotated past the corresponding stator elements 50 to produce anelectrical output. Each wind turbine 12 a and 12 b produces anelectrical output independently and directly. As described above, theelectrical output produced by the wind turbines may be DC or AC, and theelectrical output is supplied to the electrical device 22. Exhaust airis directed away from the wind turbines by the exhaust plenum 20 and isdischarged via the outlet opening 95 of the exhaust plenum, as permitteddue to the spaces or openings between frame members 36′. The outletopening 95 of the exhaust plenum 20 is maintained facing downwind, and avacuum is produced at the outlet opening 95. The torque produced by eachwind turbine 12 a and 12 b is monitored, and the torques are keptbalanced to mitigate or cancel net torque being applied to the tower 14.Net torque is controlled by adjusting the size of the air gaps for thewind turbines and/or adjusting the blade pitch angles for the windturbines. In a DC system, the sizes of the air gaps may be fixed whileletting the output voltage vary and using a charge controller to applythe output voltage to an appropriate number of battery cells forcharging. Automatic voltage control of the electrical outputs from thewind turbines may be accomplished by varying the size of the air gaps torestrict voltage changes due to changes in turbine rotational speed.

The advantages of the wind energy conversion system of the presentinvention are apparent when wind energy conversion systems having windturbines of different outer rim diameters are compared to arepresentative conventional generator having an armature two feet indiameter running at 900 rpm. A 2 ft diameter armature in a conventionalgenerator would have a circumference of π×2 or 6.283 ft. A wind energyconversion system having a wind turbine with a 10 ft diameter outer rimwould have a circumference of π×10 or 31.4145 ft.

The magnetic flux peripheral velocity of the conventional generatorrunning at 900 rpm with a 2 ft diameter armature is:

$V = {{\pi \times 2 \times \frac{900}{60}} = {94.26\mspace{14mu}{ft}\text{/}{\sec.}}}$Dividing the magnetic flux peripheral velocity of the conventionalgenerator by the circumference of the 10 ft outer rim of the wind energyconversion system

$\frac{V}{C} = {\frac{94.26}{31.4145} = {{3.000\mspace{20mu}{rps}} = {180\mspace{20mu}{rpm}}}}$This rotational speed represents the revolutions per minute that the 10ft diameter outer rim of the wind energy conversion system 10 must turnto have the same magnetic flux peripheral velocity as the conventionalgenerator having the 2 ft diameter armature running at 900 rpm or 15rps.

Table A set forth below indicates the outer rim circumference (C) infeet and the magnetic flux peripheral velocity (V) of the conventionalgenerator having the 2 ft diameter armature at 900 rpm divided by theouter rim circumference (V/C), in revolutions per second (rps) andrevolutions per minute (rpm), for outer rims having diameters of 10 ft,15 ft, 20 ft, 25 ft, 30 ft, 35 ft, 40 ft and 45 ft, thereby showing therotational speed needed for the outer rims to have the same magneticflux peripheral velocity as the conventional generator with the 2 ftdiameter armature at 900 rpm.

TABLE A Diameter C in Feet V/C = Rps V/C = Rpm 10 31.4145 3.2 180 1547.1218 2.0 120 20 62.8290 1.5 90 25 78.5362 1.2 72 30 94.2435 1.0 60 35109.9508 0.857 51.4 40 125.6580 0.750 45 45 141.3652 0.667 40

Assuming a 0.1 inch diameter wire for the stator coils of theconventional generator and a wind turbine of the wind energy conversionsystem, there would be 10 turns per inch in the stator coils. In theconventional generator having the 2 ft diameter armature, there would be6.283×12 inches per foot×10 turns per inch or 754 turns of wire in thestator coil. If the stator coil of the wind turbine is continuous alonga 10 ft diameter outer rim in the wind energy conversion system, therewould be 3,770 turns of wire in the stator coil. Accordingly, the statorcoil of the wind energy conversion system is proportionally larger thanthat of the representative conventional generator by the diameter ratio.

Since the output of a generator is a function of not only the magneticflux peripheral velocity past the stator coil but also the total numberof turns of wire in the stator coil, a full stator coil along the largerdiameter outer rim of a wind turbine in the wind energy conversionsystem reduces the rpms that the outer rim must turn to match theperformance of the conventional generator with the 2 ft diameterarmature.

Table B set forth below depicts the rotational speed in rpm needed forthe outer rim of a wind turbine in the wind energy conversion system tohave comparable power to the conventional generator with the 2 ftdiameter armature running at 900 rpm using a comparable turns per inchfor the stator coils with respect to outer rims having diameters of 10ft, 15 ft, 20 ft, 25 ft, 30 ft, 35 ft, 40 ft and 45 ft.

TABLE B Diameter Rpm 10 36 15 16 20 9 25 5.76 30 4 35 2.94 40 2.25 451.78

It is seen from the above that a wind turbine having an outer rim of 10ft diameter in the wind energy conversion system has the same magneticflux peripheral velocity at 180 rpm as the conventional generator withthe 2 ft diameter armature running at 900 rpm, and further there is fivetimes the number of turns of wire in the stator coil for the 10 ftdiameter outer rim. A wind energy conversion system having a windturbine with a 10 ft diameter outer rim and a full rim stator coiltherefore needs to turns only 180 rpm÷5×the turns=36 rpm as seen inTable B. In addition, the wind turbine of the wind energy conversionsystem may include five times the number of rotor elements or permanentmagnets along its outer rim thereby increasing the flux crossing thestator coils so that rotating a 10 ft diameter outer rim at 7.2 rpmgenerates the same power as the conventional generator having the 2 ftdiameter armature running at 900 rpm as exhibited in the following TableC showing the rotational speed needed for 10 ft., 15 ft., 20 ft., 25ft., 30 ft., 35 ft., 40 ft., and 45 ft. diameter outer rims to generatethe same power as the conventional generator.

TABLE C Diameter Rpm 10 7.2 15 2.13 20 0.90 25 0.46 30 0.27 35 0.17 400.11 45 0.08

This feature may be exploited to design shorter, discrete stator coilelements along the outer rim of a wind turbine in the wind energyconversion system rather than a full circumference stator coil and todesign complementary rotor elements or magnets which reduce the amountof material required and the cost and the weight of the wind energyconversion system. Providing a sufficient number of rotor elements ormagnets and stator coil elements restrains the rpm and reducescentrifugal forces produced on the wind energy conversion system whichalso reduces overall design costs and weight.

In a wind energy conversion system designed to produce 500 KWe at 40 mphwind with a 4 MW generator comprising one or more wind turbines asdescribed herein, the power output from the system will continue toincrease up to 80 mph wind and will continue to produce 4 MW outputpower at 80 mph and higher wind speeds. Assuming a site with an averageannual wind of 10 mph, the following Table D shows the hours of higherwind needed to equal the annual average power output at 10 mph wind.

TABLE D Equiv Equiv Wind Mph Hours Days Out KWe 10 8,760 365 9 15 2,595108 26 20 1,095 46 63 25 560 23 122 30 324 13.5 211 35 204 8.5 335 40137 5.7 500 45 96 4 712 50 70 2.9 977 55 53 2.2 1,300 60 41 1.7 1,688 6532 1.3 2,146 70 26 1.08 2,680 75 21 0.88 3,296 80 17 0.71 4,000Although each site must be evaluated for both the annual average as wellas the hours at various wind speeds to determine where to situate thewind energy conversion system, in certain geographical areas, such asthe Midwest, where winds of 80 mph are not unusual during certain monthsof the year, larger generator capacities and the ability to remainonline in high winds radically improves cost effectiveness of the windenergy conversion system.

The wind energy conversion system of the present invention can achieveweights and costs under 20% that of conventional systems per KWecapacity and allow for large generating capacities to be placed higherin the air where increased air speed further adds to the costeffectiveness of the system. The Vesta V39 has a total of 672 squarefeet of blade surface area and uses 14,313 square feet of air space tooutput 500 KWe. A wind energy conversion system according to the presentinvention having a wind turbine with a 45 foot diameter outer rim has1,590 square feet of blade area and sweeps 1,590 square feet whileoutputting 3 MW. Accordingly, the wind energy conversion systemaccording to the present invention provides six times the power outputusing one ninth the air space or 54 times the power output per acre.

Inasmuch as the present invention is subject to many variations,modifications and changes in detail, it is intended that all subjectmatter discussed above or shown in the accompanying drawings beinterpreted as illustrative only and not be taken in a limiting sense.

1. A wind energy conversion system comprising a wind turbine including astator, a blade assembly mounted for rotation about a vertical rotationaxis in response to air flow through said wind turbine and a rotorcarried by said blade assembly for rotation past said stator to producean electrical output; a hood disposed over said wind turbine defining anintake air passage for supplying intake air to said wind turbine, saidhood having an intake opening facing lateral to said vertical rotationaxis for taking in intake air and a discharge opening for dischargingthe intake air toward said wind turbine, said hood being rotatable aboutsaid vertical rotation axis to maintain said intake opening facingupwind; an exhaust plenum disposed beneath said wind turbine defining anexhaust passage for exhausting air away from said wind turbine, saidexhaust plenum having an outlet opening facing away from said verticalrotation axis for exhausting the air from said exhaust plenum, saidexhaust plenum being rotatable about said vertical rotation axis tomaintain said outlet opening facing downwind; and a tower supportingsaid wind turbine in an elevated position above the ground and a drivemechanism for rotating said exhaust plenum about said vertical rotationaxis in response to rotation of said hood about said vertical rotationaxis.
 2. The wind energy conversion system recited in claim 1 whereinsaid wind turbine is an upper wind turbine and further comprising alower wind turbine disposed beneath said upper wind turbine, said lowerwind turbine including a stator, a blade assembly mounted for rotationabout said vertical rotation axis in response to air flow through saidlower wind turbine, and a rotor carried by said blade assembly of saidlower wind turbine for rotation past said stator of said lower windturbine to produce an electrical output, said exhaust plenum beingdisposed beneath said lower wind turbine, said tower supporting saidlower wind turbine in an elevated position above the ground.
 3. The windenergy conversion system recited in claim 1 and further comprising acloseable and openable relief port in said hood, said relief port beingopenable to release excess intake air from said hood.
 4. The wind energyconversion system recited in claim 1 and further comprising a watermisting system for releasing water into the intake air.
 5. The windenergy conversion system recited in claim 4 wherein said water mistingsystem includes a water mister in front of said intake opening.
 6. Thewind energy conversion system recited in claim 1 and further includingone or more batteries and an electrical control system to allowcontrolled charging of said one or more batteries as a function ofvarying output while maintaining full output voltage via an invertersystem.
 7. The wind energy conversion system recited in claim 3 andfurther including a control system to counter-balance torque generatedby said turbines to mitigate twist torque on said tower.